(a) Field of the Invention
The present invention relates to an underground heat exchange system, and more particularly, to an underground heat exchange system capable of reducing energy consumption for operating the underground heat exchange system by dividing a medium collector storing a heat transfer medium into a plurality of parts with different installation heights and inducing the heat transfer medium to circulate by potential energy of the medium collector.
(b) Description of the Related Art
Fossil fuels, and electricity generated by fossil fuels or nuclear power, are materials most commonly used for heating, cooling, and power generation, but emissions from the burning of fossil fuels are harming water quality and polluting the atmosphere, and because our limited resources are being depleted, there is an urgent need for the development of alternative energy sources.
Wind, solar, and geothermal power are the most promising energy alternatives to fossil fuels.
In particular, research on devices using these natural energy sources for cooling, heating, and power generation is actively underway. However, there is a problem in that the wind, solar, and geothermal energy sources, though unlimited in quantity, still have not reached sufficient energy density to substitute for fossil fuels.
For example, wind and solar power installations are subject to location constraints to harvest as much energy as needed, and are also subject to preconditions such as securing a unit area of a certain size or larger.
In addition, even if these preconditions are met, ensuring energy production is difficult due to environmental factors and the costs of installation, maintenance, and management are high.
On the other hand, geothermal power can ensure steady energy supply and has the benefits of reduced installation, maintenance, and management costs.
Thus, it can be assumed that more research is being applied to geothermal cooling, heating, or power generation systems than into wind and solar power generation systems.
As can be seen from the graph in FIG. 1, no daily changes in temperature are shown at a depth of 1 m or less underground. Further, no annual changes in temperature depending on the season are shown at a depth of 6 to 7 m underground, and Korea's geology is known to be ideal for geothermal use because the soil is made up mostly of rock.
The temperature is kept steady at 15±5° C. all the year round at an underground depth of 10 m or less from the earth's surface, which makes the use of heat sources efficient, and the temperature at a deeper depth (of 1 to 2 km underground) in some areas is 80° C. and hence may be directly used for heating or the like.
A traditional geothermal cooling and heating system comes in the form of ground heat exchangers for heat exchange and a heat pump that uses a heat transfer medium to deliver heat from the ground to a space and cool or heat the space.
The ground heat exchangers are constructed in such a way that boreholes are dug 50 to 200 m deep at predetermined intervals, the ground heat exchangers are installed by inserting them into the boreholes, and adjacent ground heat exchangers are connected together and work in conjunction with a heat pump.
In this case, the ground heat exchangers are usually in the form of heat exchanger pipes that extend vertically so as to be inserted into the boreholes. However, the heat exchanger pipes, if formed to extend linearly, are limited in their contact area or time for heat exchange with the ground, thus decreasing heat exchange efficiency.
One of the technical solutions to these problems is the technology described in Korean Patent Laid-Open Publication No. 2013-0063394 (2013 Jun. 14, hereinafter, ‘conventional art’).
The conventional art relates to a ground heat exchanger and a heat exchange system using the same, and concretely discloses a technical construction that improves heat exchange efficiency by extending an underground flow path for a heat transfer medium in a predetermined shape to increase the contact area and time for heat exchange with the ground.
Although the conventional art may enhance, in part, the heat exchange efficiency of the heat transfer medium using geothermal heat, it cannot prevent energy waste caused by forcing the circulation of the heat transfer medium for heat exchange.
In particular, the ground heat exchanger according to the conventional art is constructed in the form of a pipe that bent at predetermined intervals in order to increase the contact area and time for heat exchange and this increases preliminary work for construction, such as excavation, thus resulting in high construction costs.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.